Isolation and Characterization of the Cycloparaphenylene Radical Cation and Dication

Kayahara, Eiichi; Kouyama, Takahiko; Kato, Tatsuhisa; Takaya, Hikaru; Yasuda, Nobuhiro; Yamago, Shigeru

doi:10.1002/ange.201306881

Cited by 34 publications

(4 citation statements)

References 49 publications

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“…The calculations also suggest that the radical cations have a more quinoidal contribution than the neutral compounds, judging from the BLA values of the paraphenylene units. The same trend was also observed for CPP [42] …”

Section: Resultssupporting

confidence: 83%

Synthesis of Twisted [n]Cycloparaphenylene by Alkene Insertion

et al. 2022

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Mono-alkene-inserted [n]cycloparaphenylenes 1 [(ene)-[n]CPP] with n = 6, 8, and 10, mono-orthophenylene-inserted [6]CPP 2, and di-alkene-insertved [n]CPP 3 [(ene) 2 -[n]CPP] with n = 4, 6, and 8 were synthesized by fusing CPP precursors and alkene or ortho-phenylene groups through coupling reactions. Single-crystal X-ray diffraction analyses reveal that the strips formed by the π-surfaces of 1 and 2 exhibited a Möbius topology in the solid state. While the Möbius topology in the parent 1 and 2 in solution was lost due to the free rotation of the paraphenylene unit even at low temperatures, ene-[6]CPP 4 with eight 1-pyrrolyl groups preserved the Möbius topology even in solution. Despite a twist, 1 has in-plane conjugation and possesses a unique size dependence of the electronic properties: namely, the opposite size dependency of the HOMO-LUMO energy relative to conventional π-conjugated molecules.

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Section: Resultssupporting

confidence: 83%

Synthesis of Twisted [n]Cycloparaphenylene by Alkene Insertion

et al. 2022

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“…They have gained significant attention recently ,,,,,. So far systematic studies of [ n ]CPPs have focused on their size‐dependent properties such as HOMO‐LUMO energy gaps, Raman spectroscopy, photophysical properties,, and redox potentials, and size‐complementary host‐guest chemistry ,,. [ n ]CPPs with their curved conjugated surfaces show great potential for bottom‐up synthesis of nanobelts[ 24 ] and novel donor‐acceptor nanohoop materials .…”

Section: Introductionmentioning

confidence: 99%

Mechanochemistry in [6]Cycloparaphenylene: A Combined Raman Spectroscopy and Density Functional Theory Study

Qiu

Peña-Álvarez

Baonza³

et al. 2018

ChemPhysChem

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Raman spectroscopy under high pressures up to 10 GPa and density functional computations up to 30 GPa are combined to obtain insights into the behavior of a prototypical nanohoop conjugated molecule, [6]cycloparaphenylene ([6]CPP). Upon increasing pressure, the nanohoop undergoes deformations, first reversible ovalization and then at even higher pressures aggregates are formed. This irreversible aggregation is caused by the formation of new intermolecular σ-bonds. Frequencies and derivatives of the Raman frequency shifts as a function of pressure are well reproduced by the computations. The frequency behavior is tied to changes in aromatic/quinonoid character of the nanohoop. The modeling at moderate high pressures reveals the deformation of the [6]CPP molecules into oval-like and peanut-like shapes. Surprisingly the pressure derivatives of the observed Raman mode shifts undergo a sudden change around a pressure value that is common to all Raman modes, indicating an underlying geometrical change extended over the whole molecule that is interpreted by the computational modeling. Simulations predict that under even larger deformations caused by higher pressures, oligomerization reactions would be triggered. Our simulations demonstrate that these transformations would occur regardless of the solvent, however pressures at which they happen are influenced by solvent molecules encapsulated in the interior of the [6]CPP.

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“…[10] Among the various properties of CPPs, electronic properties, as exemplified by the redox properties and orbital modulation, are among the most intriguing properties associated with the potential applications of CPPs in nanoelectronic materials. [11] Theoretical studies by Yamago and coworkers indicated that, [5b] in sharp contrast to linear oligoparaphenylenes, the HOMO-LUMO energy gap of CPPs becomes narrower as the number of phenylene rings decreases, because of the increase and decrease in the HOMO and LUMO energies, respectively (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital). Furthermore, the electrochemical analyses proved the size dependence of the HOMO-LUMO energy gap.…”

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confidence: 99%

Synthesis, Characterization, and Properties of [4]Cyclo‐2,7‐pyrenylene: Effects of Cyclic Structure on the Electronic Properties of Pyrene Oligomers

et al. 2014

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A cyclic tetramer of pyrene, [4]cyclo-2,7-pyrenylene ([4]CPY), was synthesized from pyrene in six steps and 18 % overall yield by the platinum-mediated assembly of pyrene units and subsequent reductive elimination of platinum. The structures of the two key intermediates were unambiguously determined by X-ray crystallographic analysis. DFT calculations showed that the topology of the frontier orbitals in [4]CPY was essentially the same as those in [8]cycloparaphenylene ([8]CPP), and that all the pyrene units were fully conjugated. The electrochemical analyses proved the electronic properties of [4]CPY to be similar to those of [8]CPP. The results are in sharp contrast to those obtained for the corresponding linear oligomers of pyrene in which each pyrene unit was electronically isolated. The results clearly show a novel effect of the cyclic structure on cyclic pconjugated molecules.

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Isolation and Characterization of the Cycloparaphenylene Radical Cation and Dication

Abstract: Scheme 1. Synthesis of the radical cation and dication of [8]CPP.

Cited by 34 publications

References 49 publications

Synthesis of Twisted [n]Cycloparaphenylene by Alkene Insertion

Synthesis of Twisted [n]Cycloparaphenylene by Alkene Insertion

Mechanochemistry in [6]Cycloparaphenylene: A Combined Raman Spectroscopy and Density Functional Theory Study

Synthesis, Characterization, and Properties of [4]Cyclo‐2,7‐pyrenylene: Effects of Cyclic Structure on the Electronic Properties of Pyrene Oligomers

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